The present invention relates generally to a motor or generator stator and more specifically to vibration dampers for generator or motor stators.
In certain motor or generator design situations it is necessary for the stator to be installed by shrink fit into an intermediate sleeve, which in turn is locked into the housing by either pin joint or bolt joints. The housing materials are typically made of either aluminum or magnesium which would have a higher thermal coefficient of expansion than the intermediate sleeve which would be made of a steel alloy. Therefore, during operation when heat is generated by the generator or motor, a gap may develop between the sleeve and housing at the higher operating temperatures. The gap will introduce detrimental stresses at the contact surface between the end of the sleeve and housing under vibration and thus reduce the life of the generator or motor.
U.S. Pat. No. 4,250,423 addresses these detrimental stresses by utilizing a generally cylindrical support structure for the stator of a generator where the support structure is either in the form of a housing or a support ring within the housing. The stator and support structure are formed of materials having substantially different thermal expansion rates and the stator fits within the support structure with an interference fit throughout the operating temperature range of the generator. While the support structure of the '423 patents helps to alleviate problems due to thermal stress, it does not address problems due to vibrational stress.
U.S. Patent Application No. 2004/0124720 discloses a stator assembly having first and second damping elements placed between a two part cover of the stator. The first damping elements are o-rings that are placed on both ends of the stator assembly to dampen vibration of the stator. A second damping element may also be used for additional damping. The damping elements are disposed such that a duct is formed between the two parts of the cover for passing a cooling fluid through. While this stator assembly reduces vibrational stress on the stator, it is complex, requiring two sets of damping elements on each end of the stator.
As can be seen, there is a need for a stator assembly for reducing damaging vibrations during operation of a generator or motor. It would also be desirable if such an assembly were easy and cost effective to produce.